The new coroner at the inquest into the deaths of Princess Diana and Dodi Al Fayed has warned all parties to the case to keep costs under control.
Princess Diana and Dodi Fayed's inquests are scheduled for October
Lord Justice Scott Baker was holding his first preliminary hearing at the High Court.
He insisted that "tight discipline" was necessary to keep the bill to the taxpayer within "reasonable bounds".
The judge is the fourth person to take on the role. He was appointed after Baroness Butler-Sloss resigned.
The inquests are due to begin in October.
A police investigation led by Lord Stevens concluded in 2006 that there had been no conspiracy to murder and the Paris crash had been a tragic accident.
'Heavy and constant'
Lord Justice Baker told the hearing that they must be open, fair and accurate, but that unnecessary witnesses should not be called.
He said: "The costs are going to be considerable, bearing in mind the events took place in France and many of the witnesses are French and live abroad.
"The longer the inquests last, the greater those costs will be.
"It is the duty of all of us to keep them within reasonable bounds."
Ian Burnett QC, counsel to the inquest, said they should not last longer than six months.
After further possible pre-inquest hearings in July and September, Mr Burnett said the inquests would begin on 2 October.
After the coroner's opening statement and initial evidence, French witnesses could begin giving evidence by video-link from 8 October, he added.
At the last hearing in May in front of Lady Butler-Sloss, lawyers for Dodi's father Mohamed Al Fayed, launched a bid to involve the Queen in the inquests.
The Harrods owner also wants Prince Charles and Prince Philip to be examined in the witness box.
Lord Justice Baker is one of the country's most senior judges and has more than 40 years' experience.
He has been working alongside Lady Butler-Sloss since she announced her plan to step down. She said she lacked the experience of juries needed to handle the case.
Lady Butler-Sloss had taken over the case last year after the previous royal coroner, Michael Burgess, quit blaming a "heavy and constant" workload.
The inquest process has been beset by problems and delays.
Royal coroner Dr John Burton took responsibility for the princess's body following her death in a car crash in 1997, but he retired due to ill health in 2002 and has since died.
Lady Butler-Sloss took over last September after Mr Burgess stepped down, but just three months later she was forced to back down over plans to hold the inquests in private.
Then, Mohamed Al Fayed won a judicial review against her decision to sit without a jury.
Meanwhile, Princes William and Harry have requested a swift end to the process as they prepare to mark the tenth anniversary of their mother's death this summer.
The princes spoke at length about the death of their mother in an interview broadcast on American television on Tuesday.
Prince Harry said "no-one will ever know" what happened in the tunnel where the crash took place, while Prince William said "there's not a day goes by I don't think about it".